I installed Eleutheria 20231215-01 from the F-droid reposiitory on my de-googled phone with Micro-G services core. Notifications worked perfectly out of the box. I later installed ntfy.sh and it found the cx.ring UnifiedPush server.
It is not clear to me that my notifications are in fact being served by UnifiedPush rather than FireBase.
Is the F-droid package configured by default for UnifiedPush?
How can I confirm that I am using UnifiedPush rather than FireBase?
In general de-Googling requires constant vigilance less the phone be re-Googled surreptitiously by an app.